The 100 - 900 come from the TrueType font specification. That is standard typographic convention for many years. The value can be any value between 0 and 1000 now. However, other than Adobe, not too many font foundries make fonts with weights between the 100s values.
I'll fix the typos in the working draft.
Regards,
Paul
-----Original Message-----
From: www-style-request@w3.org [mailto:www-style-request@w3.org] On Behalf Of Christoph PÃ¤per
Sent: Wednesday, August 22, 2007 4:07 PM
To: www-style CSS
Subject: Re: Why doesn't 'font-weight: 100' work yet?
Bert Bos:
CSS 3 Fontconfig Gill S. CSS 3 example names / algorithm
-----+--------+-------------+---------
+--------------------------------------
100 thin Light ^
200 extra light Light ^
300 light Light ^
400 normal book Regular Book, Regular, Roman,
Normal, Medium
500 normal Regular ^ Medium
600 demi bold Bold v
700 bold bold Bold v Bold
800 extra bold Bold v
900 black Bold v
<http://www.w3.org/TR/css3-fonts/#font-styling>
Btw., the algorithm in the current (quite old) draft of CSS 3: Fonts
requires to try to find something darker than '900', when it's not
available directly. That always returns false as far as I understand.
(There's also a "th[a|e]n" typo in the beginning of that paragraph.)
> (Fontconfig uses slant instead of font-style and thin...black
> instead of
> 100...900. We could discuss whether "book" maps to 400 or to 500, but
> for the rest the mapping is straightforward.)
Do you mean we should discuss whether 'book' should come before or
after 'normal'?
I don't know anything about fc-match and hardly more about font
weights in general, so the table above, which I assembled from your
data and the WD, appears strange to naive me:
- Why do nine steps map 3:2:4 to three available "styles", instead of
3:3:3?
- Why isn't "book" called "demi light" (or "demi bold" something else)?
- Why is book-style apparently not quite normal?
- Why doesn't CSS 'normal' match Fontconfig's?
- Why are there only two absolute keywords in CSS?
("Black" is already used for colours, but that shouldn't matter,
neven in the 'font' shorthand property.)
- Why are there unit-less numbers instead?
(Those are sometimes frowned upon elsewhere.)
- Why are they '100'-'900', not '1'-'9' or '0.1'-'0.9'?
- Why are they not expressed as percentages?
- Why is there no '0' (no ink) and '1000' (all ink)?
(Pretty useless, but closer to established numeric values elsewhere.)
- ...